Overweight and obese patients might not be the only ones who dread the number on the scale each time they visit the doctor's office.

Research shows that many physicians don't know how to constructively discuss a patient's weight, or they avoid the subject entirely.

Penn State doctors recently published a study showing that weight counseling by primary care doctors has decreased even as the nation's obesity rate has grown.

They compared patient data from the mid-1990s with data from 2007-08. Patients seen a decade later had a 46 percent lower chance of receiving weight counseling. Counseling took place in 6 percent of visits. During the same time period, the number of overweight or obese adults jumped from 52 to 63 percent.

While the authors could not offer a definitive explanation for the decrease, they noted barriers for doctors include pessimism that patients can change, time limitations during appointments and inadequate training to address the topic.

Dr. Sonia Sehgal, an instructor at the University of California at Irvine's School of Medicine, said today's future doctors are being taught how to discuss sensitive topics with patients, such as sexuality, dementia or weight.

"Over the last couple of years we've introduced some education in what's called motivational interviewing," Sehgal said. "It's a style of discussion with a patient that discusses their readiness for change. What was happening before, medicine was very paternalistic. A doctor would say, 'You have a problem with your weight. I want you to start losing weight.' The patient would say, 'Yes, yes, yes,' in the office and when they went home it wasn't realistic for their lifestyle."

Sehgal said the technique centers on the patient and doctor deciding together what the patient wants to accomplish and how to go about it.

"It's more of a discussion and a compromise and a negotiation for a shared goal of good health," she said.

Data from the National Health and Nutrition Examination Survey found that only 45 percent of overweight patients reported that they had been told by their doctors that they were overweight. For obese patients, 66 percent said their doctors had mentioned it.

Other surveys have found that doctors might mention excess weight but don't feel equipped to help their patients lose it.

Dr. Ray Nanda, medical director for Kaiser Permanente's weight-management program in Orange County, Calif., said most overweight patients he sees in his practice come in for routine health problems, not to ask about losing weight.

While looking at the patient's electronic medical record on the screen, he will ask, "How are you doing with your weight?"

"You just leave it out there in the open instead of telling someone, 'We need to talk. You've got a weight problem.' That initially sets off your defense mechanism," Nanda said.

Nanda said depending on what patients tell him, he can refer them to educational programs for help with diet and exercise.

"What I teach my doctors is you need to treat a person, not a weight problem," Nanda said. "Are you sensitive about the subject? Are you objective? Are you judgmental? Are you looking at this as a moral failure? Are you looking at things as a medical problem?"

Nanda said sometimes doctors don't want to discuss diet and exercise with their patients because they struggle in those areas too.

"I coach my doctors to even use themselves as an example, whether it's good or bad," he said. "Say, 'I, too, have trouble getting my exercise every day,' or, 'My family has these big gatherings with a lot of food.'"

34.9 percent: The obesity prevalence in Mississippi in 2011, according to the Centers for Disease Control and Prevention. It was the highest level in the nation and was based on self-reports. No state had a prevalence of obesity less than 20 percent.